Influence of n‐butanol and isomers on the combustion mechanisms of isooctane and coke formation based on ReaxFF simulation

Abstract

Fuel additives play a significant role in enhancing the thermal stability of fuel combustion. The effect of additives on the combustion of hydrocarbon fuels and the combustion performances of isooctane with three different isomer additives, (n‐butanol (1‐BuOH), diethyl ether (DEE), and 2‐butanol(2‐BuOH)), and additive‐free isooctane were explored by ReaxFF simulation in this work. The simulation system was heated to 3000 K at a heating rate of 10 K/ps and kept stable at 3000 K. A variety of combustion products (e.g., small gas molecules and C1‐C8 hydrocarbon compounds) in each system were analyzed, and the reaction paths were speculated based on the computed trajectory. The simulation results showed that the CC bond scission reaction dominated the combustion process of the three additives. All three additives promote the formation of toxic carbonyl compounds such as formaldehyde, while the pure DEE additive has the best inhibition effect on the formation of the coke precursor, C2H2, C3H4, and C3H6. The pure 1‐BuOH additive can shorten the initial reaction time of the reactants. The effects of DEE/1‐BuOH additive on the combustion of isooctane were investigated to obtain a desirable additive mixture with good performance. The expansion of the DEE proportion (80%/20% DEF/1‐BuOH) shows a slightly better coke (C3H4 and C3H6) reduction effect, while the inhibition effect is not as obvious as that of a pure DEE additive.